Compressional wave apparatus for washing articles



2, 1955 J. w. BODMAN 2,714,303

COMPRESSIONAL WAVE APPARATUS FOR WASHING ARTICLES ori inal Filed Aug. 2, 1947 JNVENTOR. JOH N W. BODMAN HIS ATTORNEYS.

United COMPRESSIONAL WAVE APPARATUS FOR WASHING ARTICLES John W. Bodman, Winchester, Mass, assignor to Lever Brothers Company, New York, N. Y., a corporation of Maine 1 Claim. (Cl. 68-3) The present invention relates to the washing of soiled articles such as clothing and the like, for example. More specifically it relates to new and improved apparatus employing compressional wave energy in cleaning liquids for washing soiled articles.

This application is a division of my copending application Serial No. 765,761, filed August 2, 1947, for Supersonic Washing, now abandoned.

The term washing as used herein is intended to cover any procedure for cleansing a soiled article by the action of a detergent-containing liquid in which the article is immersed. Any suitable liquids may be employed such as solutions of soap and a liquid in which soap is dispersible, or any of the usual dry cleaning media, for example.

Washing machines currently in use are all of the mechanical type. They differ principally in the kind of action used to produce the cleaning effect. In a very popular type, washing is accomplished by a rotating and reversing disc, usually having one or more fins mounted on its upper side, which forces hot soapy water through a fabric. Another type employs a perforated cylinder which is rotated in the washing liquid in the tub. The cylinder may be rotated in one direction only or it may periodically reverse its direction of rotation after a predetermined number of revolutions. Vacuum cups, forced up and down in the water with a radial movement, have also been used in washing machines.

Mechanical washing apparatus of the type described above is not entirely satisfactory. For one thing, it may Wear or damage fabrics during the washing operation to such an extent that their useful life is reduced. In particular, fine woolen goods cannot be washed in such apparatus since it is likely to produce felting of the wool. Further, the Washing operation is relatively time consuming and does not eifectively remove all of the soil. In some instances, it has been found that, after Washing in such apparatus, the whiteness of certain fabrics may be only half what it was before soiling.

In addition, Where relatively large amounts of soap are used in mechanical type washing machines, the mechanical agitation of the hot soapy water produces large quantities of suds. These suds form a cushion which tends to reduce the effectiveness of the washing action. Also, where the Wash water is hard and contains lime salts, for example, the mechanical agitation produced is not suflicient to prevent precipitated lime soaps from being deposited on the fabrics being washed and discoloring them.

The principal object of the present invention, accordingly, is to provide new and improved Washing apparatus that is free from the above-noted deficiencies of the prior art.

Another object of the invention is to provide new and improved apparatus by means of which soiled articles may be made cleaner in less time than has been possible, heretofore, without damage to the articles.

A further object of the invention is to provide new rates Patent Cfiice 2,714,303 Patented Aug. 2, 1955 and improved washing apparatus of the above character in which the washing action is produced by compressional wave energy, preferably of relatively high frequency.

The objects of the invention are attained by contacting a soiled article with a detergent-containing cleaning liquid in the presence of compressional wave energy.

In a typical embodiment, the articles to be Washed are immersed in a suitable detergent-containing cleaning liquid in a container and compressional waves are set up in the liquid by suitable magnetostriction wave generating means. The latter may comprise, for example, a magnetostriction rod secured at its upper end to a diaphragm mounted flush with the bottom of the container. The rod is mounted midway between its ends in a housing which carries windings connected to a suitable source of relatively high frequency. The interior of the housing may serve as a conduit for a cooling fluid to dissipate heat generated in operation of the apparatus.

With the novel apparatus of the invention, remarkable washing eifects can be obtained in a simple and highly effective manner. Since the washing action is produced by compressional wave energy in the washing liquid, fabrics are not subjected to undue wear or damage and fine woolen goods can be effectively washed without fear of felting. Further, a shorter period of time is required for washing and the wash is whiter. Also, no undesirable cushion of suds is formed even when relatively large quantities of soap are employed. Moreover, it has been found that the high frequency compressional wave energy employed tends to keep any lime soaps that may be formed dispersed in the Washing liquid. Hence, there is considerably less likelihood of a fabric becoming discolored from lime soap being deposited thereon when washed according to the present invention.

Additional objects and advantages of the invention will be apparent from the following detailed description of a representative embodiment, taken in conjunction with the accompanying drawing, which is a schematic diagram of magnetostriction oscillator apparatus for washing soiled articles in accordance with the present invention.

Referring now to the single figure, magnetostriction oscillator washing apparatus is shown which comprises a substantially cylindrical upper container 10 communieating with a lower container 10a of lesser diameter. In the lower container 101: is disposed a magnetostriction rod 11. The rod 11 may be of any suitable material showing an appreciable magnetostriction effect such as, for example, Monel metal, nickel, Stoic metal, Invar, or other suitable alloy and it is mounted substantially midway between its ends in a supporting ring 12.

At its upper end, the magnetostriction rod 11 is mounted in a watertight diaphragm 13, the outer circumference of which lies flush with the bottom wall of the cylindrical container 10. The diaphragm 13 and the upper face 14 of the rod 11 cooperate with the upper cylindrical container 10 to form a container for a Washing liquid 15 in which soiled articles such as articles of clothing 16 are adapted to be immersed. Preferably the articles of clothing 16 are suitably supported on racks 16a, for example.

Around the lower container 10a are formed two windings 17 and 17a which are connected in a conventional magnetostriction oscillator circuit. Specifically, one terminal of the coil 17 is connected by a conductor 18 to the control grid 19 of a conventional triode 20. The filament 21 of the triode 29 is connected by a conductor 22 to the positive terminal of a grid biasing battery 23, the negative terminal of which is connected to the other terminal of the coil 17.

One terminal of the coil 17a is connected by a conductor 24 to the plate electrode 25 of the triode 20, which is also connected through a condenser 26 to the control grid electrode 19. The other terminal of the coil 17a is connected to the positive terminal of a source of plate voltage 27, the negative terminal of which is connected to. the conductor 22.

It is well known that when a rod of magnetostriction material is placed inside a'coil through which alternating current is flowing, as illustrated in the single figure, the: rod. will vibrate longitudinally, i. e., willv lengthen and shorten at the frequency of the alternating current, provided. there is a steady polarizing magnetic flux supplied by either residual magnestism, permanent magnetism or direct current flowing in the coil. When the frequency of the supplied current approximates the mechanical resonant frequency of the rod to longitudinal vibrations, the intensity of the vibrations, becomes very great. If the polarizing magnetic flux is omitted, the rod. will vibrate at twice the applied frequency since positive and negative flux have identical magnetostrictive effects.

When the oscillator circuit shown in the single figure is energized, the rod 11 vibrates longitudinally at a relatively great intensity, producing compressional waves of given frequency which are transmitted through the, washing liquid 15 to the articles of clothing 16. As a result of this intense longitudinal vibration, the rod 11 tends to become hot and it is desirable, therefore, toprovide suitable cooling means to carry away the heat. To this end, the lower cylindrical container a may be used as a water jacket 28 which receives cooling water from an inlet 29 and discharges it from an outlet 30 as shown, suitable openings (not shown) being provided in the supporting ring to enable water to pass therethrough.

In testing the apparatus of the present invention, samples of different kinds of cloth were used and standard conditions of soiling were established. Both a natural soil and a standard artificial lampblack soil were employed. The former was obtained from conventional vacuum cleaning apparatus of the type used in cleaning carpets and the like, after screening to remove lint and large particles. For test purposes, cloth samples were thoroughly impregnated with this soil.

The artificial lampblack soil used in the tests was prepared by dispersing 5 grams of mild soap tallow, 3 grams of deodorized kerosene and 2 grams of fine lampblack in approximately 200 cc. of carbon tetrachloride. This dispersion was diluted in additional carbon tetrachloride in the proportions of one part dispersion to ten parts of carbon tetrachloride to form a standard solution. Test samples were soiled by immersing in the standard solution and then drying.

The effectiveness of the washing action was determined by comparing the white reflectance of the cloth sample after washing with its original reflectance before and after soiling. Reflectance values for the samples were obtained on a Beckman spectrophotometer with a reflectance attachment and a standard MgO block. Light of about 550 mu (5500 Angstroms) and a slit width of .15 mm. were employed.

In an actual test of the apparatus disclosed in the single figure, a 3' inch diameter circular patch of wool having an unsoiled white reflectance of about 58% was soiled with a standard carbon tetrachloride soil in the manner described above to a reflectance of about 21%. The soiled wool sample Was suspended in the washing liquid in the container 10, which comprised only ordinary tap water having a hardness of approximately 60 p. p. m. at a temperature of about 120 F. The magnetostriction oscillator shown in the single figure was designed to operate at about 8,000 cycles per second and in the test delivered approximately 10 watts of energy to the rod 11 for a period of 10 minutes. After washing and drying, the measured reflectance of the sample was found to be-about In a second test, a soap solution was used instead of water in the container 10 and it comprised a solution of approximately 0.4% mild soap in ordinary tap water having a hardness of approximately p. p. m. at a temperature of about F. The oscillator was again turned on for a period of 10 minutes, after which the sample was dried and its reflectance measured. The reflectance value found for this condition was approximately 44% which represents a better cleaning efiect than can be obtained with a conventional mechanical type washing machine.

It willv be apparent from the foregoing that extraordinary washing effects can be obtained by means of the apparatus of the invention in a much shorter time than can be obtained with conventional mechanical type washing apparatus.

The reasons for the extraordinary washing effects obtained in accordance with the invention are not clearly understood. In the conventional mechanical types of washing apparatus, it appears that the flexing of the cloth which is produced by the mechanical agitating means ordinarily used is an important factor in the washing action. However, it does not appear to be a material factor in the washing method of the invention since tests have been conducted with cloth samples rigidly supported between rings, so that no substantial flexing of the cloth sample was possible. Further, no appreciable flexing of the cloth has been observed in numerous tests that have been made.

It is possible that, because of the different physical properties of the cloth and the soil with which it is soiled, the dirt may be moved independently of the cloth and that this may be an important factor in the washing effects observed. However, this theoretical explanation has not been confirmed by actual tests and it is not intended to restrict the scope of the invention in any way.

In addition to the extraordinary washing effects noted above, it appears that good washing effects can be obtained in accordance with the invention with somewhat less soap in the solution than would be required to produce the same results with existing conventional mechanical apparatus. Tests have indicated that when a soap solution is subjected to compressional wave energy of relatively high frequency, preferably in the supersonic range, alternate clear and cloudy striations are formed in the liquid. It has been found that there is relatively little soap in the clear regions, whereas the concentration of soap in the cloudy regions is quite high. Accordingly, if a weaker than normal soap solution is used, the concentration of soap will nevertheless be relatively high at the nodes of the standing waves produced in the washing solution. This concentration can be made sufl'icient to produce a good washing action even with a weaker soap solution than would be normally required.

The striations can be eliminated by increasing the intensity of the wave energy or by producing relative movernent between the cloth and the standing wave in any desired manner without changing the wave intensity, as disclosed in the copending application of Seym ore Goldwasser, Serial No. 783,050, filed October 30, 1947, for Methods and Apparatus Utilizing Supersonic Waves for Washing, for example, patented Sept. 1, 1953, No. 2,650,872.

It appears that washing takes place either by transmission of compressional wave energy through the soiled article or by reflection of the wave energy therefrom.

It has been found that a certain threshold of power must be exceeded before any appreciable washing effect is produced. This threshold of power appears to be a function of the physical properties of the soiled articles being Washed. For various materials such as rayon, rayon $3 pends on the type of material, the thickness, thread size, and the physical properties of any coating materials that may have been used. In general, anything presenting an interface changes the loading properties of the article. Obviously, the threshold also depends to some extent on the amount and nature of the soil present in the cloth. By way of example, cotton sheeting soiled with standard vacuum cleaner soil requires wave energy of only approximately half the intensity required to wash cotton sheeting soiled with carbon tetrachloride soil.

For any given type of soil, cleaning liquid and material comprising the articles to be washed, an optimum frequency can be selected for the waves which will insure an optimum cleaning effect in a minimum amount of time without appreciable wear of, or damage to, the articles to be washed. At the outset, the frequency should be high enough to insure a high enough intensity to overcome the threshold for the particular type of material, bearing in mind that for a given amount of energy, the intensity varies as the square of the frequency. On the other hand, it should be low enough to prevent any sub stantial energy loss by cancellation of waves reflected from the top and bottom surfaces of the material or by transmission of wave energy through the material. The optimum frequency for any material will be, in general, the one that gives the maximum amount of power with minimum loss from cancellation or transmission through the material.

Although good results can be obtained with compres sional wave energy having a frequency in the upper part of the audible frequency band, preferably a supersonic frequency should be used. In general, supersonic frequencies are those above the audible band, namely, above 15,000 to 20,000 cycles per second.

it will be understood from the foregoing that the invention provides highly novel apparatus for washing soiled articles by means of which extraordinary washing effects may be produced in a much shorter time than has been possible heretofore. Further, these effects have been obtained without any noticeable damage to the articles being washed. In fact, in the case of clothing, it is believed that Washing can be done with less damage to the fabric than occurs when conventional mechanical washing apparatus is employed.

The invention will have special utility in laundries, for example, where large numbers of flat pieces like towels, sheets, etc., would be washed in washing apparatus constructed according to the invention and then conveyed to other apparatus such as ironers, for example, for other operations.

The reference herein to a detergent is intended to include soap and non-soapy synthetic higher fatty organic detergents, as Well as inorganic detergents such as borax, trisodium phosphate and the like.

The reference to a dispersion or dispersed is intended to include a dispersion in the form of a colloidal dispersion as well as in the form of a solution.

The soaps include those which are well recognized as suitable for use in a laundering operation and are more particularly any of the alkali metal higher (8 or more carbon atoms) carboxylates or mixtures thereof which are dispersible (including soluble), especially in warm or hot water such as employed under laundering conditions. Amine and ammonium soaps are also contemplated. Ex-

amples are lithium oleate, potassium stearate, sodium oleate, sodium iinoleate, sodium or potassium myristate or palmitate, ammonium oleate, triethanolamine stearate, sodium or potassium abietate and other rosin acids, and sodium and/or potassium soaps of mixtures of fatty acids such as are present in tallow, cocoanut oil and similar soap making fats. These are referred to generally as laundering soaps.

Examples of non-soapy detergents include the alkali metal or amine alkyl sulfates, such as sodium cetyl sulfate and potassium lauryl sulfate, the alkyl aryl sulfonates, -iore particularly ones having 8 to 24 carbon atoms in the alkyl radical and an aryl radical of benzene or naphthalene, the taurine condensation products such as RiCONRXSOslVle where R1 is a high fatty radical, R is a lower alkyl radical and X is a hydrocarbon chain, and Me an alkali metal or amine, the condensation production of an alkali metal isethionate and a higher fatty acid, etc.

Further examples of organic detergents and other surface active agents are described in Industrial and Engineering Chemistry, vol. 35, at pages 107 to 117 and 126 to 129. Any of the wide variety of synthetic higher fatty organic detergents here disclosed are suitable.

When the solution is non-aqueous, such as a hydrocarbon or a chlorinated hydrocarbon, as is conventionally used in dry cleaning, any of these organic detergents may be used, providing they are soluble in the particular solvent employed in the cleaning operation.

The specific embodiment described above is intended to be merely illustrative of the invention and should not be regarded as limiting it in any way. The invention is susceptible of numerous modifications in form and detail within the scope of the appended claim.

I claim:

in apparatus for cleaning soiled articles including a container for soiled articles and a cleaning liquid, the com bination of a diaphragm in a wall of the container, a tubular housing mounted over said diaphragm externally of the container and having fluid inlet and outlet connections, a magnetostriction rod supported substantially midway between its ends within said housing and having one end extending through said diaphragm in watertight relation thereto and in contact with the cleaning liquid, windings surrounding said housing for magnetically coupling With said rod, and an oscillator circuit connected to said windings for causing said rod to vibrate at substantially the natural frequency of longitudinal vibration therein.

References Cited in the file of this patent UNITED STATES PATENTS 1,750,124 Pierce Mar. 11, 1930 2,037,568 Emmerling et al Apr. 14, 1936 2,116,522 Kunze May 10, 1938 2,203,479 Witwer et a1 June 4, 1940 2,219,348 Turner, Jr Oct. 29, 1940 2,468,550 Fruth Apr. 26, 1949 2,478,207 Robinson Aug. 9, 1949 2,495,295 Spanier Jan. 24, 1950 FOREIGN PATENTS 372,762 Great Britain July 25, 1931 

